1. Field of the Invention
This invention relates generally to millimeter wavelength, electromagnetic energy, dielectric waveguide transmission line components, and more particularly to a bandpass filter apparatus.
2. Description of the Prior Art
T. Itoh, in a chapter entitled "Dielectric Waveguide-Type Millimeter-Wave Integrated Circuits", of Vol. 4 of Infrared and Millimeter Waves, Academic Press, Inc., 1981, has a section headed Resonators and Filters. The bandpass filters described therein are of the ring resonator type.
G. L. Matthaei et al, in an article entitled "Some Dielectric-Waveguide Filter Structures", describes several dielectric waveguide filters. This article is found in the 1983 IEEE MTT-S Digest. A bandstop filter is formed using notches in the sides. A bandpass filter uses a coupled grating design approach.
R. A. Stern et al, in U.S. patent application Ser. No. 310,542, filed Oct. 13, 1981, entitled "Dielectric Waveguide Circulator", now U.S. Pat. No. 4,415,871 issued Nov. 15, 1983, disclose a millimeter wavelength dielectric circulator of the Y-junction type; however, no bandpass filter apparatus is described herein.
R. W. Babbitt et al, in U.S. patent application Ser. No. 409,201, filed Aug. 18, 1982, entitled "Frequency Scan Antenna Utilizing Supported Dielectric Waveguide", now U.S. Pat. No. 4,468,673 issued Aug. 28, 1984, disclose an antenna structure having periodically spaced transverse slots cut in the upper surface of the waveguide; however, no bandpass filter apparatus is disclosed therein.
R. A. Stern et al, in U.S. patent application Ser. No. 394,753, filed July 2, 1982, entitled "Supported Dielectric Waveguide Transmission Line and Components", now abandoned disclose a dielectric support arrangement for millimeter wavelength dielectric waveguide transmission lines and line components.